What is the theme in The Art of Racing in the Rain: A Novel by Garth Stein?

Dog as man's best friend is another theme in the book. Enzo comments frequently on his role as Deny's best friend. To Enzo, his friendship with Danny rests on the reality that Enzo cannot speak. Therefore, the dynamic that exists between them is fundamentally determined according to this one facet. The Art of Racing in the Rain is a work of fiction and as such, Enzo's narration is proof that he processes information in much the same way as Denny Swift.